Programming: $*$

Write a function in $C_{+}+$with the name reversedoubly that has a doubly linked list as input. The function

returns the linked list with the values in reverse order. For example, when the function has the input

linked list:

$1*5*7*4*3-6*9$

the function will change the values of each node of the linked list to:

$9\mathrm{.}6-3-4-7-5-1.$

Note: The function does not print the values on the screen.